No description available.

As a nation that depends so heavily on its infrastructure, the United Statescontinually seeks to better maintain the investment that it has made in its roadways.Asphalt pavements make up the majority of the paved roadways in the United States andultimately contribute to the bulk of the expense of highway maintenance. The goal ofthis research was to develop a means for taking a simple measurement of pressure atvarious interfaces on and within an asphalt pavement structure in an effort to directlyassess the damaging effects of different wheel loadings. It is well known that everincreasing wheel loads and other unusual wheel loading conditions are detrimental to theeffort of maintaining the roadways. The results of the data can be compared to the classicempiricalistic and mechanistic approaches to asphalt pavement design and analysis, aswell as the more modern finite-element computer modeling programs. The Tekscanmeasurement system, which utilizes a very thin matrix based pressure sensitive sensor,has been deemed applicable for measuring pavement pressures. Various types of wheelloadings have been considered throughout this study. It was determined that the type oftire, tire inflation pressure, applied load, and the asphalt itself all have an effect on theresultant pressures on the surface of and within an asphalt pavement structure. Thisresearch may contribute to the understanding of pressure distributions at the tire/asphaltinterface depending on the type of tire, adjustments in tire inflation pressure, and varyingthe wheel load. The results may lead to a better understanding of pressure distributions atvarying depths within an asphalt pavement structure. The ability to quantify thesevariables could assist designers when analyzing and designing asphalt pavements.

The thesis investigates the mechanisms and restraints which influence transverse crack propagation through the bituminous surfacings of semi-flexible pavements. These pavements incorporate continuously laid cement bound roadbases which, during curing, crack into slabs of varying length, ranging from 4-25m. Reciprocal crack growth can occur in the surfacing, known as 'reflection cracks', located through stresses concentrated at the discontinuities within the roadbase . Three mechanisms have been identified and are described as contributing to reflection crack propagation. They have been analysed independently although the majority of conclusions drawn are applicable to their combined action. Their relative importance will vary with respect to pavement geometry, material properties, environmental conditions and traffic intensity. The first mechanism, 'tensile fatigue', induces crack propagation vertically upward through the surfacing. Tensile strains are developed during daily and ru1nual fluctuations of temperature, which cause expansion and contraction of the cement bound roadbase. This mechanism is most prominent on pavements with thin surfacings and long slab lengths. The rate of crack growth is dependent on the range of temperature within the roadbase , slab length, thermal characteristics of the roadbase material and resistance of the surfacing to this form of fatigue . A model has been developed based on a combination of results from an extensive testing programme, the use of fracture mechanics theory and computer simulation of the condition. The results quantify the resistance shown by conventional bituminous mixes to reflection cracking in terms of their mix parameters. Also considered are the use of stress relieving membranes, reinforcement material and modified binders to inhibit crack growth. The second mechanism, 'tensile yield' is also thermally induced but associated with cold weather conditions. Temperature gradients through the pavement structure induce warping and contraction within the uppermost layers. Tensile strains developed at the surface can, under U.K. winter temperatures, exceed the ultimate yield strain of the wearing course material. Preliminary. investigations of four pavements constructed in the early 1970's to motorway specifications indicate that reflection cracking will initiate at the surface if the yield strain, as defined through tensile creep tests, is reduced through binder oxidization to a value of 0.5%. This mechanism will operate on pavements with greater structural layer thicknesses and is only partially dependent on slab length. The influence of a further mechanism, 'shear fatigue' induced through trafficking of the pavement, has been shown to be confined to the acceleration of crack growth in the final stages of propagation unless a breakdown of interlock occurs between adjoining roadbase slabs.

Maintaining a functioning road network is a challenge in today’s society due to the financial restrictions faced by all levels of government. A means of determining how to efficiently spend their limited funding must be found. In addition, the concept of sustainable development is rapidly growing in today’s world pressuring municipalities towards operating in a more socially and environmentally friendly manner. Sustainability is broken down into three aspects which are economical, social and environmental. A truly sustainable pavement satisfies its functional requirements while aiding social and economic development and minimizing negative environmental impacts In response to the growing sustainability trend, the City of Markham is committed to incorporating sustainability into their daily operations. This thesis is the result of a research project with the City of Markham which is directed at incorporating sustainable practices into pavement engineering. The objective of this project is to provide a practical framework for incorporating pavement sustainability best practices into the pavement engineering operations at the City of Markham. This practical framework is developed through the completion of four primary objectives. The first main objective involves the completion of a comprehensive literature review that identifies and reviews the state-of-the-art sustainable pavement best practices. This literature review is divided into five pavement related categories which examine: materials, design and construction techniques, maintenance and rehabilitation techniques, sustainability evaluation systems and carbon footprinting. The second objective involves the quantification of the environmental, economic and carbon footprint impacts of the reviewed pavement best practices; this evaluation is conducted using PaLATE. PaLATE is an excel based software developed at the University of California for evaluating the economical and environmental impacts of various pavement technologies. The third objective involves the utilization of GreenPave for evaluating the environmental friendliness of the analysed pavement best practices. The green discounted life cycle cost (GDLCC) is calculated to include the economic aspect of sustainability. The final objective involves the development of project and network level frameworks. These two frameworks are connected which forms the final framework for incorporating sustainability into City of Markham’s pavement engineering operations. Guidelines for the proper utilization of the developed framework are provided. Through the completion of the literature review it is concluded that there is a wide variety of sustainable pavement technologies that range from project design to pavement decommission. PaLATE analysis results indicate that warm mix asphalt and full depth reclamation are the most environmentally friendly construction and rehabilitation techniques, respectively. Including recycled asphalt pavement (RAP) within pavement mix designs reduces both costs and environmental impacts. Excluding microsurfacing, full depth reclamation was the least expensive rehabilitation technique while hot mix asphalt with RAP was the cheapest construction technique. The same initial construction and rehabilitation techniques are evaluated using the GreenPave rating system. Pervious concrete scored the highest rating under the initial construction category with warm mix asphalt a close second. Cold in place recycling, cold in place with expanded asphalt and full depth reclamation all scored the highest under the rehabilitation category. In the future, the City of Markham may wish to alter the GreenPave rating system to be more reflective of municipal practices as the current version of GreenPave is weighted more heavily on high volume roads. To include the economical aspect, the green discounted life cycle cost (GDLCC) is calculated for all techniques. Hot mix asphalt with RAP and full depth reclamation resulted with the lowest GDLCC in the construction and rehabilitation categories, respectively. Finally, the recommended project and network level frameworks for incorporating sustainability into the pavement engineering practices at the City of Markham are proposed. On the project level, GreenPave evaluation and project level GDLCC aid decision makers in determining the most sustainable project alternative. On the network level, a pavement management system (PMS) serves as the platform. The role of a PMS is to provide recommendations on when and where rehabilitation is required and which rehabilitation technique is the most sustainable. The cost effectiveness and network level GDLCC indicators also aid pavement engineers in making network level decisions. The project and network level frameworks are connected to provide a complete pavement management framework for incorporating sustainability. The framework provides economic benefits by increasing the effectiveness of budget allocation; this is accomplished by maximizing the overall condition index gained to dollar spent ratio. The environmental benefits of this framework include the minimization of harmful gas emissions, project carbon footprints and energy and water consumption. The social issues of pavement projects are unique to each case and therefore must be addressed case by case. A common starting point when addressing these issues is provided.

Master of Science / Department of Civil Engineering / Mustaque Hossain / The Kansas Department of Transportation is transitioning from adherence to the 1993 American Association of State Highway and Transportation Officials (AASHTO) Pavement Design Guide to implementation of the new AASHTO Mechanistic-Empirical Pavement Design Guide (MEPDG) for flexible and rigid pavement design. This study was initiated to calibrate MEPDG distress models for Kansas. Twenty-seven newly constructed projects were selected for flexible pavement distress model calibration, 21 of which were used for calibration and six that were selected for validation. In addition, 22 newly constructed jointed plain concrete pavements (JPCPs) were selected to calibrate rigid models; 17 of those projects were selected for calibration and five were selected for validation. AASHTOWare Pavement ME Design (ver. 2.2) software was used for design analysis, and the traditional split sampling method was followed in calibration. MEPDG-predicted distresses of Kansas road segments were compared with those from Pavement Management Information System data. Statistical analysis was performed using the Microsoft Excel statistical toolbox. The rutting and roughness models for flexible pavement were successfully calibrated with reduced bias and accepted null hypothesis. Calibration of the top-down fatigue cracking model was not satisfactory due to variability in measured data, and the bottom-up fatigue cracking model was not calibrated because measured data was unavailable. AASHTOWare software did not predict transverse cracking for any projects with global values. Thus thermal cracking model was not calibrated. The JPCP transverse joint faulting model was calibrated using sensitivity analysis and iterative runs of AASHTOWare to determine optimal coefficients that minimize bias. The IRI model was calibrated using the generalized reduced gradient nonlinear optimization technique in Microsoft Excel Solver. The transverse slab cracking model could not be calibrated due to lack of measured cracking data.

abstract: The accurate prediction of pavement network condition and performance is important for efficient management of the transportation infrastructure system. By reducing the error of the pavement deterioration prediction, agencies can save budgets significantly through timely intervention and accurate planning. The objective of this research study was to develop a methodology for calculating a pavement condition index (PCI) based on historical distress data collected in the databases from Long-Term Pavement Performance (LTPP) program and Minnesota Road Research (Mn/ROAD) project. Excel™ templates were developed and successfully used to import distress data from both databases and directly calculate PCIs for test sections. Pavement performance master curve construction and verification based on the PCIs were also developed as part of this research effort. The analysis and results of LTPP data for several case studies indicated that the study approach is rational and yielded good to excellent statistical measures of accuracy. It is believed that the InfoPaveTM LTPP and Mn/ROAD database can benefit from the PCI templates developed in this study, by making them available for users to compute PCIs for specific road sections of interest. In addition, the PCI-based performance model development can be also incorporated in future versions of InfoPaveTM. This study explored and analyzed asphalt pavement sections. However, the process can be also extended to Portland cement concrete test sections. State agencies are encouraged to implement similar analysis and modeling approach for their specific road distress data to validate the findings. / Dissertation/Thesis / Masters Thesis Civil Engineering 2015

South Africa is a country fortunate in possessing a well developed network of paved roads that provides a basic and often overlooked facility for the social and economic welfare of the country. However, an accute shortage of funds available for pavement rehabilitation is endangering the integrity of this network, making continuous research for improved and more economical rehabilitation procedures necessary. I believe that this thesis, provides in a need for improved techniques, as a uniform approach is advocated, incorporating the best available procedures applicable throughout the country. In compiling the document, specific attention was given to current South African practice, ensuring that the recommended procedures are based on the use of readily available equipment and techniques familiar to engineers in this country. Guidelines to all the main stages of rehabilitation investigations are contained in a logical and systematic procedure of investigation, evaluation, analysis, rehabilitation design and finally. economic appraisal of applicable options. In the process full use is made of past pavement behaviour and pavement condition, thereby making possible an early assessment of additional information needed. Although evaluation and analysis procedures are suggested for use, no formal method in this regard is excluded, provided the method is relevant to the case and information obtainable will benefit the analysis in terms of the probable influence on the best rehabilitation strategy to follow. By assessment of the value of information obtainable, much emphasis is placed on the optimum utilization of available resources in designing the best applicable remedy to an existing problem. This procedure is demonstrated by the inclusion of a study that I undertook in co-ordination with the Transvaal Roads Department for the NITRR. This case study demonstrates the applicability of the various evaluation, analyses and rehabilitation design methods, and the use of decision trees in an economic analysis to select the best applicable rehabilitation option. In conclusion the consequences of implementation to date are investigated. Recommendations for further research and possible improvements for future revisions of the recommended procedure are finally looked at. / Dissertation (MSc)--University of Pretoria, 1984. / gm2014 / Civil Engineering / unrestricted

Mechanistic-Empirical (M-E) methods are the cornerstone of current pavement engineering practice because of their enhanced predicting capabilities. Such predicting power demands richer input data, computational power, and calibration of the empirical components against distress measurements in the field. In an effort to spearhead the transition to M-E design in Uruguay, the aim of this Project is twofold: (1) develop an open-source, MEPDG-based, simplified M-E tool for Uruguayan flexible pavements [Product-One], and (2) compile a library of Uruguayan input data for design [Product-Two]. A functional, Matlab-based beta version of Product-One with default calibration parameters and a first collection of Uruguayan input data are presented herein. The Product-One beta is capable of designing hot-mix asphalt (HMA) structures over granular bases on top of the subgrade. Product-Two features climate information from the INIA weather station network, traffic distribution patterns for select Uruguayan highways, standard-based (Level-3) HMA properties, and Level-3 and Level-2 unbound materials' parameters. Product-One's outcomes were against other available M-E software, as a means to test the code's performance: Product-One reported a distress growth similar to CR-ME (MEPDG-based) on default calibration parameters but different to MeDiNa (calibrated core). In conclusion, Product-One managed to perform like another MEPDG-based software under the same design inputs and constraints, accomplishing one of this Thesis' objectives. However, Product-Two could not be created to the initially-desired extent. Nevertheless, the author remains confident that significant leaps forward can be made with little extra effort and further research on M-E design can be encouraged from this project. / Master of Science / The design of pavement structures historically relied on methodologies developed after experimental results, the so-called “empirical methods”. Advances in technology over the recent years allowed for more complex but more reliable methods – the mechanistic-empirical (M-E) methods – to finally be adopted by practitioners both in the US and abroad. In an effort to encourage the transition to M-E design in Uruguay, this project aimed at developing an open-source M-E design tool for Uruguayan flexible pavements based on the American MEPDG design methodology [Product-One], and assembling a library of Uruguayan data necessary for design with such an M-E method [Product-Two]. In this project, a beta version of the Product-One design tool for the design of asphalt-surfaced pavements and a collection of climate, traffic distribution, and materials’ properties data from Uruguayan sources for design is presented (load information was not available for this project); this Thesis is the log of the data collection effort as well as the guide to using and understanding all the components of Product-One. In addition, Product-One has been tested by comparing its pavement design results for a given Uruguayan highway against other M-E design software tools: MeDiNa and CR-ME. Product-One’s outcomes resembled the results given by CR-ME (also MEPDG-based) but differed with those from MeDiNa (crafted specifically for design of Brazilian roads). In conclusion, Product-One managed to perform like another MEPDG-based design tool under the same inputs and constraints, accomplishing one of this Thesis’ objectives. However, some of the Uruguayan information sought for could not be retrieved and so added to Product-Two. Anyway, the author remains confident that both Products can be significantly improved with little extra effort and that this project may encourage further research on M-E design.

The following study is a demonstration of the effectiveness of porous pavement and an infiltration trench as Best Management Practices (BMPs) in the reduction of stormwater and its constituents. The field work of the study was conducted from 1986 through 1988 and the report was written in 1990 and finalized in 1996. Results of the study show that porous pavement and the infiltration trench significantly reduced the volume of stormwater runoff as well as its constituents from an urban parking lot area. In addition, wetfall and dryfall were found to be the major contributors to the runoff loading and yet were not comparable to associated studies. Peak and total flow runoff volumes were reduced significantly thereby reducing the overall pollutant loading. Antecedent dry period was found to be related to pollutant loading but only up to about 5 days total. / Master of Science

Energy harvesting technologies have drawn much attention as an alternative power source of roadway accessories in different scales. Piezoelectric energy harvesting consisting of PZT piezoceramic disks sealed in a protective package is developed in this work to harness the deformation energy of pavement induced by traveling vehicles and generate electrical energy. Six energy harvesters are fabricated and installed at the weigh station on I-81 at Troutville, VA to perform on-site evaluation. The electrical performance of the installed harvesters is evaluated by measuring the output voltage and current generated under real traffic. Instant and average power outputs are calculated from the measured waveforms of output voltage and current. The analysis of the testing results shows that the electrical productivity of the energy harvesters are highly relevant to the axle configuration and magnitude of passing vehicles. The energy transmission efficiency of the energy harvester is also assessed. / Ph. D.